The present invention relates to a piezoelectric device, such as used for example in filter structures.
Due to their high resonance frequencies and their high quality, in particular in mobile radio communication, bulk acoustic wave (BAW) resonators have been widely used. A simple implementation of a BAW resonator comprises a thin layer of piezoelectric material arranged between two metal electrodes.
In ladder-type filters based on BAW resonators a non-linear behavior has been observed, for example in antenna-duplexers which operate directly at the antenna of mobile phone systems and transmit power levels exceeding certain power values. This problem arises for example when 0.1 W.